Spark plug



March 10, 1931. A CHAMPION 1,795,638

SPARK PLUG Filed Jan. 7, 1929 nvmwoz ac-eased Patented Mar. A10, 1931 'UNITED STATES' )PATENT oFFlcle'.l

ALBERT CHAMPION, IIJECEASED,v LATE OF FLINT, MICHIGAN, :BY BASII: W. DE GUI- CHARD, OF FIJINT, MICHIGAN, AND DETROIT TRUST COmANY, 0F DETROIT, MICH- IGAN, EXECUTORS, ASSIGNORS TO A C SPARK PLUG COMPANY, OF FLINT, MICHI- GAN, A CORPORATION 0F MICHIGAN snm PLT/re Application led January 7, 1929. Serial No. 330,824.

cuit or current jump between the terminal and shell it has been necessary to extend the insulator core for some distance beyond the top of the shell; the effectiveness of the'insulator being dependent upon the length of its surface. However, inthe event the surface of the insulator becomes wet or-dirty, as sometimes Voccurs in use, the'current will ilash or travel over the surface instead of jumping at the contact points.'

To reduce the tendency toward short circuiting or current travel between thetermi'- nal and shell is one of the objects of the present invention, which contemplates the use of a flash arrester comprising a collar of insulating material placed `upon the core between the terminal and shell, having an annular flange, which serves to increase -the effective surface of the core and also as a shield for keeping the core dry and clean.

The invention will be more clearly understood by reference to the accompanying drawing in which Figure 1 is a vertical sectional view of a spark plug on which a collar is secured in accordance with the present invention. Figures 2, 3 and 4 are detail perspective views partly in section, showing alternative forms of the collar, that shown in Figure 2 being of the type associated with the spark plug in Figure 1.

Referring to the drawing by reference characters, the numeral 1 indicates a shell having a 'dependent extension 2 which is screw threaded for engagement within an opening in the engine cylinder block leading to the combustion chamber. Carried by the shell is an insulator core 3- of porcelain, quartz or other nonconducting material, through a central bore of which extends the current conducting wire or electrode 4, having a contact point at its lower end in spaced relation with the electrode 5 carried by the sc rew threaded extension 2, which space constitutes a spark gap across which the current normally flashes. At the upper end of the terminal 4 there is formed a screw threaded enlarged portion or stud 6 on which ma be threaded a nut, so as to provide a bin ing post or connector for a current conducting wire. Ihe collar 8 having an outwardly pro- )ecting annular web or flange v9 is secured upon the periphery of the core adjacent the top thereof. The collar preferably consists of rubber or other similar non-conducting material, and the hole or opening through the center of the collar has a diameter slightly smaller than that of the core, whereby the inherent elasticity of the collar holds it snugly about the core. Formed on the inside of the collar are a pair of ribs or beads 10, which are adapted to extend into a similar p air of peripheral grooves in the upper portion of the core 3, -providing an interlock to hold the collar on the core.

The collar 12 shown in Figure 3, having an annular iange 13, is provided with a smooth interior surface 14 and is particularly intended for use with insulator cores that have smooth peripheral surfaces, as distinguished from the grooved -type shown in Fig-4 ure 1. If desired, the inner surface of the collar 13 may be slightly tapered to conform with the taper on thecore 3. In Figure 4, the collar 16 basa downwardly and outwardly flaring'portion 17 terminating in an an-v nular rim 18, forming a cup-shaped sleeve which affords a more effective shield or cover to protect the core againstywater andlirt.

It will be understood that more than one collar may be used on a sin le spark plug if such/ is found desirable. or instance, the collar shown in Figure 3 could be placed midway down the core and beneath the collar A8 in Figure 1.

From the above description it will be apparent that the outwardly proj ectmg web 1n 'terposed between the terminal and shell and extending through the path of mutual attragtion, protects the core from rain and water and also increases the surface areaover which 5 the current must pass, thereby minimizing the possibility of a short circuit and serving te arrest flash over-between the terminal and grounded shell.

What is claimed is:

1. 'Alash arrester for spark plugs and the like, comprising a collar of elastic insulating material having an annular outwardly pro-' jecting web and a central apertured hub provided with an internal bead that is adapted to extend in interlocked 'relation through the inherent elasticity of the collar into a corresponding peripheral groove of the spark plug part on which the collar is to be fitted.

v 2. For use -as an accessory 'with a Aspark plug having an insulator core between a central electrode and an outer electrode shell and which core extends@i considerable distance beyond the top of the shell to the 'termi-` nal' connection `of the electrode and is pro z5 vided adjacent its upper end with a peripheral groove, a spark Hash arrester comprising an annular disc or the like of elastic insulating material provided witlra central aperture of a diameter initially smaller than that of the.

core for fitting the disc on the core in snug en gagement by reason of its inherent elastlcity and an internal annular bead formed on the disc inside said aperture forinterlocln and seating engagement within the perip eral groove at the top of the core; l

3. 'In a Hash arrester for use as an accessory with a spark plug having an insulator core between an internal electrode andan external electrode carrying shell and which core '40 extends a considerable distance beyond the top ci the shell to the terminal connector at the upper end of the electrode, and is provided adjacent its upper end with a f peripheral groove, said arrester comprised of a plate-like' member of elastic insulatin material havin a central hub to be expaned and snap onto the upper end ofthe core, and characterized byv an internal bead within the hub for projection into said peripheralgroove of the 5o core.v

BASIL W. DE GUICHARD,-

DETROIT TRUST COMPANY, By MGPHERSON BROWNDG,

l r wewtors of Albert Deceased: 

